Xavier Aptitude Test 2019 Paper

Total number of apples =1+2+3+4+...+n =

n(n+1)

2

Now,

n+(n+1)

2

≤150
⇒n(n+1)≤350
lf n = 16, then n(n+1)=16×17 =272≤350
If n = 16, then n (n +1) = 17 × 18 = 306 > 350
Hence, in the fruit shop, apples are initially in 16 rows.
Total number of apples initially =

16×17

2

=136
Now, 136−126=10
And 1+2+3+4=10
Hence, apples in the top 4 rows had sold, when 126 apples remained in the shop.
∴ Total number of rows having 126 apples left =16−4=12